This invention relates to a process or method for removing an oxygen-containing gas from the head space of a container partially filled with a liquid product typically cured by an oxygen-containing gas. Specifically, it relates to a process for substituting a gas or blend of gases for atmospheric air (which contains approximately 21% oxygen) in the head space of a container to prevent an oil-based product or finish (e.g., paint, stain, varnish, polyurethane, and the like) from curing (i.e., hardening, gelling, skinning over, etc.) with oxygen.
Even a tightly sealed container filled with leftover paint, stain, varnish, or other oil-based finish, will thicken, gel, or skin over with time. This occurs because the oxygen that is sealed in the storage container continues to react with oil-based finishes. When these finishes are stored, enough oxygen can be trapped inside the container to cure and thicken the product, eventually forming a skin over the top. The thickening of the product during storage ultimately degrades the product and its original chemical composition.
Historically, there are several non-patented prior attempts to eliminate the head space in a container filled with left over oil-based finish. Some inventors have tried to eliminate the air space in a container filled with left-over oil-based finish by placing marbles or rocks in the liquid. This is thought to xe2x80x9cfillxe2x80x9d up the container and eliminate the head space. In addition to contaminating the oil-based finish, the cleaning of the marbles results in lots of wasted time and product. Another prior attempt was to transfer the liquid to a smaller container to reduce the air space, but this often resulted in inventory tracking and contamination problems. Since the labeling was on the original container, tracking the instruction labels and warnings was also a problem. Yet another prior attempt is to try to store the leftovers upside down which would only guarantee that the skin will form on the xe2x80x9cbottomxe2x80x9d of the liquid. The leftover oil-based finish will still be ruined. Finally, attempts were made to physically exhale into a container before it is sealed. However, the air we exhale is not oxygen free (in fact, it will support life). We inhale 21% oxygen and exhale approximately 15% oxygen. Therefore, this attempt fails to protect the leftover finish.
Hayashi, et al., U.S. Pat. No. 4,602,473; Mizandjian, et al., U.S. Pat. No. 4,870,801; and Marano, et al. U.S. Pat. No. 5,452,563 are directed to inert gas preservation in other industries such as food. These prior art examples are directed to a different problem than the one solved by this invention. In the food industry, oxygen promotes bacteriological growth and furthers the decay of perishable goods. In contrast, the method of the present invention isolates a chemical necessary for the curing of non-food liquid products such as a finish resin that is cured by an oxygen-containing gas.
The process and method described here for displacing oxygen from the head space of a container filled with oil-based finish is based on proven technology.
The present invention provides a method or process for preserving a non-food liquid product during storage. The method consists of displacing air or other oxygen-containing gas from the head space of a container containing the non-food liquid product such as an oil-based product using an inert gas or a blend of inert gases and sealing the container after the oxygen has been displaced. The inert gas or blend of inert gases used must be heavier than oxygen.
The process of preserving oil-based products during storage by use of an inert gas or a blend of inert gases that is heavier than oxygen has many advantages over prior attempts in that:
(1) It saves money by allowing consumers to use 100% of their oil-based products. No product is wasted and, thus also reduces the amount of hazardous waste and preserves our environment and resources.
(2) It is a simple and smart process for flushing oxygen from the head space of a container. Time will be saved when starting the next finishing job since there is no skin to clean off the top of the finish, the finish will not have to be filtered, and the original finish chemistry is ensured.
(3) It will compliment other tools used in the trade, such as spray guns or paint brushes. Spray guns will no longer get clogged and brushes will maintain their functional use. This allows work to be performed faster and more reliably.
(4) It will prevent changes in product chemistry during storage. This allows for higher quality consistency and repeatability in finishing jobs.
(5) By using an inert gas or a blend of inert gases that is heavier than oxygen to purge oxygen from containers filled with oil-based finishing product, a long term deficiency has been corrected with a simple, smart chemical remedy.